Transition metal mediated homogeneous catalysis is an indispensable component of modern organic synthesis, rendering a given non-catalytic-process into a truly efficient one. The transition metals are modified by organic ligands to obtain highly selective reactions at higher rates. Especially P and N-containing ligands have been successfully implemented in important organic reactions. The well-designed catalysts serve for carbon-carbon and carbon-heteroatom double bond reduction reactions. Particularly, chiral organic ligands provide a powerful access to a wide variety of enantiomerically pure compounds. The properties of these catalyst are influenced by both the characteristics of the metal and those of the ligands associated with the metal atom. The asymmetry of the metal-catalyzed process is induced, for example, by the chiral ligand scaffold. Therefore, the development of the highly efficient chiral ligands plays a crucial role in expanding the utility of transition metal catalyzed asymmeric reactions. A large and diverse range of ligands have been designed and prepared for use in asymmetric catalysis. The number of novel chiral ligands is growing rapidly. For example, biaryl atropoisomeric ligands have been explored as effective class of a steadily increasing family of axially chiral ligands. Among them, the most well-known example is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP), the synthesis and first application of which was reported by Noyori et al. (A. Miyashita, A. Yasuda, H. Takaya, K. Toriumi, T. Ito, T. Souchi, R. Noyori J. Am. Chem. Soc. 1980, 102, 7932). Many variations of the of atropoisomeric biphenyl diphosphines have been reported in the meantime. Substituted in the 6,6′-position 2,2′-bisphosphino-biphenyls are known as BIPHEP-family (G. Svensson, J. Albertsson, T. Frejd, T. Klingstedt Acta Crystallogr. 1986, 1324; R. Schmid, M. Cereghetti, B. Heiser, P. Schönholzer, H.-J. Hansen Helv. Chim. Acta 1988, 71, 897; R. Schmid, J. Foricher, M. Cereghetti, P. Schönholzer Helv. Chim. Acta 1991, 74, 370.) The working-group of Zhang has described TunaPhos with tuneable dihedral angles by introducing a bridge with variable length to link the chiral atropoisomeric biaryl groups (S. Wu, W. Wang, W. Tang, M. Lin, X. Zhang Org. Lett. 2002,).

Sannicolo et al. have reported the first example of a diphosphine ligand TMBPT, where the biarylic system was replaced by a bi-heteroarylic system (T. Benincori, E. Brenna, F. Sannicolo, L. Trimarco, P. Antognazza, E. Cesarotti Chem. Commun. 1995, 685). In designing this ligand, it was to achieve to compare the novel geometry of the interconnected five-membered rings with well-known biphenylic systems. A further example of a diphosphine ligand containing a dipyridyl backbone is P-Phos which was prepared by Chan et al. (J. Wu, W. H. Kwok, K. H. Lam, Z. Y. Zhou, C. H. Yeung, A. S. C. Chan Tetrahedron Lett. 2002, 43, 1539-1543). Knochel et al. introduced new types of ferrocene ligands (M. Lotz, G. Kramer, P. Knochel Chem. Commun., 2002, 2546-2547)
Recently, Gilbertson et al. have reported that vinyl phosphines are readily accessible through ketones by palladium-catalyzed coupling of the corresponding vinyl triflate with diphenylphosphine (S. R. Gilbertson, Z. Fu, G. W. Starkey Tetrahedron Lett. 1999, 40, 8509-8512). The group has developed novel chiral P,N-ligands starting from commercial available (1S)-(+)-ketopinic acid (S. R. Gilbertson, Z. Fu Org. Lett. 2001, 3, 161-164). The known camphor enol triflate undergo facile coupling with arylzinc reagents to afford arylbornene (G. Stork, R. C. A. Isaacs J. Am. Chem. Soc. 1990, 112, 7399-7400). Knochel et al. used this method for the preparation of new P,N-ligands from readily available chiral building blocks such as (R)-camphor and (R)-nopinone. (T. Bunlaksananusorn, K. Polbern, P. Knochel Angew. Chem. 2003, 115, 4071-4073)
